The present invention relates to a vacuum fluorescent display and, more particularly, to a built-in chip vacuum fluorescent display which is mounted with driver chips within a vacuum tube.
Generally, vacuum fluorescent displays (VFDs) may be classified into various formats depending upon the structure, the display area, the display content, and the manner of driving. Particularly in view of the display area, the VFDs can be classified into a usual type, a front luminescent type, and a dual layer type. In view of the display content, the VFDs can be classified into a number display type, a character display type, and a graphic display type.
The graphic display type VFD has phosphors patterned in a dot matrix type corresponding to the picture signal information, and driver chips for selectively driving the grid electrodes. For example, assume that the graphic display type VFD with a dot matrix of 128xc3x97128 is driven in a fourfold or eightfold manner. When only the phosphors (the anode electrodes) are driven while omitting the drivers for driving the grids, the number of anode electrodes interconnected via the same wiring line amounts to 512 with the fourfold driving manner, and to 1024 with the eightfold driving manner. Accordingly, even with the use of a 128 bit driver, four driver chips should be provided with the fourfold drive type VFD, and eight driver chips with the eightfold drive type VFD.
The driver chips are mounted on a glass placed at the inside or outside of a vacuum tube outlining the VFD by way of a mounting technique called chip on glass (COG) or chip in glass (CIG). For example, such a structure is disclosed in U.S. Pat. No. 5,739,634.
When the mounting of the driver chips is made by way of the COG or CIG technique, the driver chips, the phosphors and the anode electrodes are provided at the same substrate. Therefore, it becomes necessary for an additional space for mounting the driver chips to be provided as compared to the VFD wherein the driver chips are not mounted within the vacuum tube. For this reason, the size of the vacuum tube becomes needlessly enlarged to accommodate the increase in area unnecessary for the display purposes.
Such a problem becomes serious in the graphic display type VFD mounted with large numbers of driver chips within the limited effective area.
In the case of a graphic display type VFD with a dot matrix of 128xc3x97128, when four or eight driver chips are mounted in accordance with the CIG technique, the non-effective area for mounting the driver chips at the inside of the vacuum tube is at best in the range of 15xcx9c25 mm from the periphery of the effective area. Consequently, as the area for mounting the driver chips is extremely limited, it becomes difficult to design the structure of the VFD in a suitable manner.
In accordance with the present invention a built-in chip vacuum fluorescent display is provided which can be effectively mounted with a plurality of driver chips within a vacuum tube.
According to one aspect of the present invention, the built-in chip vacuum fluorescent display includes a vacuum tube having a transparent top substrate, a bottom substrate facing the top substrate with driver chip wirings while being spaced apart from the top substrate with a predetermined distance, and a side glass disposed between the top and the bottom substrates while interconnecting the top and the bottom substrates. A plurality of driver chips are mounted at the bottom substrate within the vacuum tube while being electrically connected to the driver chip wirings. At least one subsidiary substrate is provided at the space between the top and the bottom substrates within the vacuum tube while having wirings electrically connected to the driver chip wirings. Cathodes are provided between the subsidiary substrate and the top substrate within the vacuum tube to emit thermal electrons. Anodes with phosphors are patterned at the subsidiary substrate while being electrically connected to the wirings.
According to another aspect of the present invention, the built-in chip vacuum fluorescent display includes a vacuum tube having a transparent top substrate with first wirings, a bottom substrate facing the top substrate with driver chip wirings while being spaced apart from the top substrate with a predetermined distance, and a side glass disposed between the top and the bottom substrates while interconnecting the top and the bottom substrates. A plurality of driver chips are mounted at the bottom substrate within the vacuum tube while being electrically connected to the driver chip wirings. At least one subsidiary substrate is provided at the space between the top and the bottom substrates within the vacuum tube while having second wirings electrically connected to the driver chip wirings. Cathodes are provided between the subsidiary substrate and the top substrate within the vacuum tube to emit thermal electrons. First anodes with phosphors are patterned at the top substrate while being electrically connected to the first wirings. Second anodes with phosphors are patterned at the subsidiary substrate while being electrically connected to the second wirings.
According to still another aspect of the present invention, the built-in chip vacuum fluorescent display includes a vacuum tube having a pair of main substrates facing each other while being spaced apart from each other with a predetermined distance, and a side glass disposed between the main substrates while interconnecting the main substrates. A subsidiary substrate is provided between the main substrates. Anodes are patterned at the subsidiary substrates with phosphors. The phosphors emit light upon landing of thermal electrons emitted from cathodes. A grid controls the thermal electrons landing on the phosphors. A plurality of driver chips are mounted at one of the main substrates within the vacuum tube to selectively drive either the anode or the anode and the grid.
The driver chip wirings and the wirings are electrically connected to each other by way of bonding wires.
The driver chips have output terminals electrically connected to the driver chip wirings by way of bonding wires.
The phosphors are patterned in a dot matrix type for display graphic images.